Johann George Hartmanns, Universitäts-Mechanici zu Halle, Nöthiger Unterricht von Verbesserung der Sack-Uhren

Rare first and only edition of Hartmann's technical guide to clockmaking, issued together with an improved edition of his guide to constructing pocket-watches. The two works are embellished with 54 figures on 17 folding plates, not to mention the engraved portrait of the author, a resident clock-maker in Jena. Hartmann's third chapter is devoted to a subject evidently of wide contemporary interest — the application of clocks to astronomical measurements.